Camshaft adjuster

ABSTRACT

An arrangement of a camshaft adjuster which has a drive wheel, a stator and a rotor. The camshaft adjuster is held together via sleeves arranged coaxially with respect to the axis of rotation.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of DE 10 2010 063 703.3 filed Dec. 21, 2010, which is incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a camshaft adjuster.

BACKGROUND OF THE INVENTION

Camshaft adjusters are used in internal combustion engines in order to vary the control times of the combustion chamber valves. Adaptation of the control times to the current load reduces the consumption and the emissions. A widespread design is the vane cell adjuster. Vane cell adjusters have a stator, a rotor and a drive wheel. The rotor is generally connected to the camshaft for conjoint rotation. The stator and the drive wheel are likewise connected to each other, wherein the rotor is located coaxially with respect to the stator and within the stator. Rotor and stator form oil chambers which can be acted upon by oil pressure and permit a relative movement between stator and rotor. Furthermore, the vane cell adjusters have diverse sealing covers. The assembly of stator, drive wheel and sealing cover is formed via a plurality of screw connections.

DE 10 2008 029 692 A1 shows an assembled camshaft with a vane cell adjuster. Said vane cell adjuster is fastened to the camshaft end by a central screw. All of the individual parts are fixed and braced at the camshaft end by means of the central screw. A sealing cover is subsequently connected to the drive wheel, sealing cover and drive wheel together creating an oil-tight space.

SUMMARY OF THE INVENTION

It is the object of the invention to specify a camshaft adjuster which is of particularly simple construction and has a reliable connection to the camshaft.

According to the invention, this object is achieved in that the camshaft adjuster has a drive wheel, a stator and a rotor. The rotor has a degree of freedom of rotation in relation to the stator, and the rotor is fixed axially in relation to the stator. The camshaft adjuster has an adapter sleeve and a connecting sleeve arranged coaxially with respect to the axis of rotation of the drive wheel. The adapter sleeve and the connecting sleeve are firstly connected to each other and secondly fix the rotor, stator and drive wheel in place axially.

The effect achieved by this is that a plurality of axially bracing connections in the camshaft adjuster are dispensed with. The rotor, the adapter sleeve and the connecting sleeve form a conjointly rotating unit which can be connected to one camshaft end. A multiplicity of screws, rivets and pins can be dispensed with as a result.

In a refinement of the invention, the adapter sleeve is designed to be connectable to one camshaft end. In this case, the camshaft end is designed in such a manner that the adapter sleeve is centered via a collar or step. Said centering minimizes concentricity errors. Furthermore, that end of the adapter sleeve which is on the front side and faces the camshaft forms an advantageously planar contact surface with the camshaft in order to absorb high forces, The centering means and the contact surface can advantageously be textured on the surface by, for example, knurling, in such a manner that the reliability of the connection is increased.

In an advantageous refinement, the adapter sleeve is of oil-conducting design. The conducting of oil through the adapter sleeve forms short oil paths, and low oil losses can be obtained by the coupled components having a small number of sealing points. Further sleeves used in the camshaft adjuster can likewise be of oil-conducting design. The sleeves used can be provided with sealing elements.

In a particularly preferred refinement, the adapter sleeve and the connecting sleeve have one or more axial stops. Said stops form positional fixing, wherein the rotor is braced and the drive wheel and the stator are provided with a small amount of axial play. The integral formation of said stops in the form of changes in diameter on the outer surface areas of the adapter sleeve and of the connecting sleeve is advantageous here.

In a refinement of the invention, the adapter sleeve has a mounting for the drive wheel. The adapter sleeve is advantageously designed to be connectable by the mounting directly to the camshaft end. Since a camshaft mounting is generally arranged at the camshaft end, forces are advantageously absorbed at the cylinder head.

In a preferred development, the adapter sleeve is connected to the connecting sleeve by a thread. The possibility of removal is advantageous in this case. Internal and external threads and left-handed and right-handed threads can be used in this case. Furthermore, a thread-rolling formation on one of the two sleeves is conceivable.

In a further refinement of the invention, the connecting sleeve is braced to the adapter sleeve by a connection with an allowance for fit or an interference fit. The effect achieved by this is that, when the camshaft adjuster is installed at the camshaft end, the central screw further reinforces and secures the interference fit. The interference fit can be designed more efficiently by milling the surfaces of the sleeves.

In one development of the invention, the stator is connected in a form-fitting manner to the drive wheel and is centered on the latter. The form-fitting connection transmits the torque from the drive wheel to the stator. With the centering, a seal forming an oil-tight space in the stator can be provided. The axial holding together between the stator and the drive wheel is formed via axial stops and by the connection between adapter sleeve and connecting sleeve.

As an alternative, in order to form the torque transmission between stator and drive wheel, use may also be made of pins, rivets or other standard parts. The advantage of using standard parts is the low production costs.

In an advantageous development of adapter sleeve, connecting sleeve and the outside diameters thereof, the drive wheel, the stator and the rotor are particularly well centered with respect to one another and a very precise positioning with respect to one another is achieved. For this purpose, the outside diameters are designed to differ in diameter from one another. Drive wheel, stator and rotor are advantageously centered on a common outside diameter which can be produced simply and cost-effectively.

Functions, such as centering and axial fixing in place, can optionally he realized via further sleeves. For this purpose, for example, one of the sleeves can have a centering means for a stator and a further sleeve can have a centering means for a rotor, etc. Any combination of the functions and the number of sleeves is conceivable.

In an optional refinement of the invention, the adapter sleeve, the connecting sleeve and optionally further sleeves can be connected to one another with additional means. Means of this type may be screws, disks, rings, pins or the like.

In a particularly preferred development, the sleeves have a passage opening for the penetrating arrangement of a central screw which fastens the camshaft adjuster to the camshaft end. A sealing cover or a covering hood, which seals off the unit in an oil-tight manner in relation to the environment, can subsequently be arranged on the unit.

Further individual parts of the adjustment unit, such as sealing covers, bearings, locking units or oil-conducting plates, can be fixed in place by the adapter sleeve and the connecting sleeve and by additional sleeves.

In an advantageous refinement, the assembly of stator, rotor and drive wheel and of further components is formed via just one sleeve. In this case, the components to be mounted are inserted onto the sleeve, centered and brought against the stops of the sleeve, and the assembly created is subsequently secured. Securing means may be snap rings, securing rings, nuts, screws or, advantageously, the sleeve itself. In this case, the material of the sleeve is crimped, bent or deformed in some other way. Formation of the sleeve in sheet metal is advantageous.

In a particularly preferred development of the invention, the end surface of the adapter sleeve on the camshaft side has an encircling depression concentrically with respect to the center axis. Said depression is connected to oil supply bores of the camshaft. Axially parallel bores which intersect said depression extend in the adapter sleeve. The bore outlets open out at the other end of the adapter sleeve in a first oil chamber. Furthermore, the adapter sleeve has a concentric passage opening. Said passage opening is penetrated by a central screw. In this case, a gap remains between central screw and diameter of the passage opening. Said gap constitutes a further means of supplying oil. The adapter sleeve has radial oil bores which connect the outside diameter to the inside diameter of the passage opening. In this case, the radial oil bores are designed to he offset at an angle to the axial oil bores so that the bores do not intersect and therefore there is no short circuit in the oil circuit. The radial oil bores advantageously open out into the outside diameter, which constitutes the bearing point for the drive wheel, in order to lubricate said bearing point. As an alternative, the radial oil bores may also open out into an encircling groove from which the oil is then conducted further into the corresponding oil chamber.

The oil ducts can optionally be arranged in an oil-conducting sleeve oriented at an angle to an oil supply source. In order to be able to realize an angle-oriented supply of oil between the sleeves, the sleeves have elements securing against rotation. A reliable arrangement of the oil ducts can therefore be formed.

Furthermore, a sleeve can have a thread for fastening to a camshaft. As a result, the fastening with a central screw can advantageously be omitted, and the sleeves are formed without a passage bore for a central screw. The thread can be designed as an internal or external thread and can advantageously have a left-handed or right-handed thread based on the direction of rotation of the drive wheel.

As an alternative, in order to reduce the weight, the sleeves used can be designed to be hollow on the inside, or to be perforated or slotted or in the form of a cage. In order to increase the rigidity, the cavities can have a filling, for example made of metal foam.

In a concretization of the invention, a hub which is located at one end of the stator formed on the stator. Said huh can advantageously be determined by the sheet metal thickness of the stator. The hub supports the stator on a sleeve, preferably the connecting sleeve.

A spring element is arranged between the stator and the rotor. The spring element braces the stator to the rotor in an advantageous direction. The coil body of the spring is advantageously mounted or guided on an outside diameter of one of the sleeves used, for example the adapter sleeve. The spring can optionally also be guided on the huh of the rotor or of the stator or on other components.

In a further development of the invention, the sleeves used, or at least one thereof, is designed as a sheet metal part. This reduces production costs. As an alternative, use may also be made of other manufacturing methods, such as sintering, extrusion, deep drawing or milling. Accordingly, the use of a multiplicity of materials, such as metals, plastics or composite materials, is conceivable. In order to minimize wear, coatings can be provided.

In a favored development of the invention, the camshaft adjuster is fastened to the camshaft end by a central screw. The central screw penetrates the sleeves which are used and which hold together the camshaft adjuster per se. The screw head makes contact in the assembly with one of the sleeves, preferably the connecting sleeve. In this case, it is advantageous for the camshaft adjuster to be able to be preassembled by the use of sleeves and to subsequently be able to be fastened to the camshaft just with a central screw.

In a further refinement of the invention, the central screw has a concentric passage opening which extends from the screw head as far as the end on the thread side. Said passage opening is used for the oil conduction. The oil conducting means is advantageously designed as a means of venting or recycling the oil emerging from the stator into the covering hood into the cylinder head.

In a refinement of the invention, the oiltightness is ensured by means of a covering hood. The covering hood is advantageously mounted subsequently after assembly of the adjuster. The covering hood can have a sealing ring. As an alternative, a sealing cord, for example consisting of liquid plastic, can be applied, advantageously prior to assembly, to the covering hood and then, upon fitting of the latter, produces the sealing function.

In an advantageous refinement, the covering hood has snap-on hooks which are distributed around the circumference and can engage in complementary openings in the drive wheel and connect the two components to each other. In this case, the covering hood is advantageously formed from plastic or sheet metal.

The covering hood can be fastened to the camshaft adjuster with a further sleeve or with a sleeve which has already been used.

An arrangement without a covering hood may be advantageous in order to form a “belt in oil” camshaft adjuster.

By means of the arrangement according to the invention of sleeves, in particular an adapter sleeve and a connecting sleeve, and the action of said sleeves, a compact camshaft adjuster assembly is produced, which assembly can be connected to one camshaft end by an advantageous formation of a sleeve. Distortions due to local screw connections are avoided, and an increased service life and low production costs are achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are illustrated in the figures, in which:

FIG. 1 shows a section through a camshaft adjuster which is fastened to one camshaft end;

FIG. 2 shows a sleeve which is designed as an adapter sleeve;

FIG. 3 shows a further view of FIG. 2;

FIG. 4 shows a section through a connecting sleeve;

FIG. 5 shows a drive wheel which can be mounted on the adapter sleeve; and

FIG. 6 shows a section through the mounting of the drive wheel on the adapter sleeve.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a camshaft adjuster 1 and a camshaft end 5. The camshaft adjuster 1 has a drive wheel 2, a stator 3, a rotor 4, a disk 47, a locking means 6, a restoring spring 7, and an adapter sleeve 9 and a connecting sleeve 10. In this case, the arrangement furthermore has a central screw 8 and a covering hood 46.

The camshaft adjuster 1 is designed as a vane cell adjuster, wherein pressure chambers (not illustrated specifically), which can be pressurized with oil, are formed between the rotor 4 and the stator 3. Oil is supplied via the camshaft end 5 through the oil bores 18, 19 and through the oil bores 20 which opens out into a gap between the screw stem 24 of the central screw 8 and an inside diameter of the central camshaft bore 15. In this case, the oil passes first of all into the adapter sleeve 9, from which the oil can be conducted by means of further arrangements of oil bores and oil grooves the interior of the camshaft adjuster 1 and to the pressure chambers. The formation of the oil conduction through the adapter sleeve is explained in FIG. 2 and FIG. 3.

The drive wheel 2 is mounted on the adapter sleeve 9. A rotor 4, which is of cup-shaped design in the form of a deformed part, adjoins the latter, by means of an integrated locking means 6, in the axial direction coaxially with respect to the drive wheel 2 and the disk 47. The rotor 4 is mounted on the adapter part 9 by means of a hub. A stator 3, which is likewise of cup-shaped design in the form of a deformed part, surrounds the rotor 4 and the disk 47. The disk 47 serves here as a sealing element. The stator 3, at one end thereof, is centered and connected in a form-fitting manner on a step 23 to the drive wheel 2 so that torques of the drive wheel 2 can be transmitted to the stator 3. The restoring spring 7 is arranged within the rotor 4 and outside the adapter sleeve 9. The restoring spring 7 braces the rotor 4 rotatably to the stator 3. The connecting sleeve 10 is subsequently connected to the adapter sleeve 9 such that the rotor 4 is braced to the connecting sleeve 10 and the adapter sleeve 9 for conjoint rotation and at the same time the components fitted one inside another, such as drive wheel 2, stator 3, rotor 4, are axially secured. At the same time, the components are centered by the assembly of adapter sleeve 9 and connecting sleeve 10. There is a small amount of play in the radial direction and axial direction between the connecting sleeve 10 and stator 3 so that deformations arising from the operation cannot result in jamming.

Furthermore, FIG. 1 shows that the camshaft adjuster 1 is fastened to the camshaft end 5 for conjoint rotation by means of a central screw 8. In this case, the camshaft adjuster 1 is arranged together with the adapter sleeve 9 on a receptacle 21 of the camshaft end 5. The adapter sleeve 9 and the receptacle 21 together form a means of centering the camshaft adjuster 1. In addition, a covering hood 46 is connected to the drive wheel 2 by a snap connection. A seal 12 forming the camshaft adjuster in an oil-tight manner is provided between covering hood 46 and stator 3. Venting by means of a coaxial venting duct 11 formed in the central screw 8 guides leakage oil to a further section of the camshaft bore 15 and back to the venting bores 16 in the camshaft end 5. In this case, a thread 25 locally separates off the camshaft bore 15 the venting bores 16 from the oil supply 20.

A camshaft adjuster 1 shown according to FIG. 1 can be assembled such that first of all a drive wheel 2 is fitted onto the adapter sleeve 9, followed by the disk 47. Subsequently, the rotor 4 is fitted together with the locking means 6, the stator 3 and the restoring spring 7 such that the restoring spring 7 can act between the stator 3 with the rotor 4 and, by means of locking, the locking means 6 defines a position of stator 3 and rotor 4. Stator 3, rotor 4, restoring spring 7 and locking means 6 are subsequently then pushed coaxially onto the adapter sleeve 9 in such a manner that the rotor 4 finds an axial stop and a centering means on the adapter sleeve 9, the stator 3 being centered on the drive wheel 2 for conjoint rotation.

This assembly which is created is subsequently secured by the connecting sleeve 10.

Furthermore, the camshaft adjuster 1 can then be fastened to one camshaft end 5 by a central screw 8 and optionally, in the case of a design of a traction mechanism drive without oil, can be formed in an oil-tight manner with a covering hood 46.

FIG. 2 shows an adapter sleeve 9 which is of oil-conducting design. The oil can be conducted through the oil bores 20, which are mentioned at the beginning and are not illustrated in this figure, from the central bore 26 via radial oil bores 32 to an oil groove 31, which then distributes the oil around the circumference and said oil is conducted through further duct formations (not illustrated) between stator and drive wheel into a first working chamber. A second working chamber is supplied by the oil bores 18, 19 mentioned at the beginning, wherein the oil is then conducted further via oil bores 33 which open out into the restoring spring centering means 29. The adapter sleeve 9 has a central bore 26 which is provided for the penetration by a central screw 8. The axial stop 27 is provided for fixing the drive wheel 2 in place on the hearing diameter 28. Oil can be conducted via the oil groove 31 to lubricate the bearing point of the drive wheel 2.

Furthermore, the adapter sleeve 9 has a restoring spring system 34 and a restoring spring centering means 29. The axial stop 35 at the tapering end of the adapter sleeve 9 is provided for fixing a rotor in position. The rotor here is connected frictionally against said stop 35 for conjoint rotation by means of the connecting sleeve 10. The centering 30 of the rotor forms an aligned and coaxial arrangement of the rotor with respect to the axis of rotation 22. The inside diameter of the central bore 26 has a thread (not illustrated specifically).

FIG. 3 shows a further view of the adapter sleeve 9 and the opening out of the oil bores 33 into an axial oil groove 36 on the end side. The oil groove 36 on the end side is bounded here in a sealing manner by the stop 27 and the central bore 26. The radial oil bores 32 open out on the inside into the central bore 26 and on the outside into the encircling oil groove 31 on the bearing diameter 28.

FIG. 4 shows a sleeve which is designed as a connecting sleeve 10. The connecting sleeve 10 here has a thread 38 and a central bore 37. In order to brace the rotor 4 with the adapter sleeve 9, an axial stop which extends radially outward is formed. Said stop is adjoined by a step 40 which constitutes a play-associated bearing point for a stator 3. By means of a further axial stop 41, the stator 3 and also the drive wheel combination are held together by the stop 27, which is mentioned in FIG. 2, of the camshaft adjuster 1. The lugs 42 form a complementary shape for the engagement of a tool with which the connecting sleeve 10 can he fitted.

FIG. 5 shows the formation of a drive wheel 2 in sheet metal. In this case, the drive wheel 2 has a toothed contour 13 for a toothed belt and a rim 14 for the positional fixing of same. Furthermore, a hub 43 is arranged on the central bore 44 of the drive wheel 2. Bulges 45 which are distributed uniformly around the circumference extend between hub 43 and toothed contour 13 and are arranged in an alternating manner with the configuration of a step 23 in the direction of rotation about the axis of rotation 22. Via said configurations of the step 23 and the bulges 45, oil ducts can be formed and a form-fitting connection for transmitting a torque between stator and drive wheel realized.

FIG. 6 shows a detailed view of the drive wheel 2 with the central bore 44 thereof in the hub 43 on the bearing diameter 28 of the adapter sleeve 9. When the camshaft adjuster 1 is installed at the camshaft end 5, the stop 27 which is designed as a step is enclosed by the receptacle 21 so as to realize centering via the diameters of said bearing point, an oil supply and sheet-like contact.

List of Reference Numbers 1) Camshaft Adjuster 2) Drive Wheel 3) Stator 4) Rotor 5) Camshaft End 6) Locking Means 7) Restoring Spring 8) Central Screw 9) Adapter Sleeve 10) Connecting Sleeve 11) Venting Duct 12) Seal 13) Toothed Contour 14) Rim 15) Camshaft Bore 16) Venting Bores 17) Axial Bearing 18) Oil Bore 19) Oil Bore 20) Oil Bore 21) Receptacle 22) Axis of Rotation 23) Step 24) Screw Stein 25) Thread 26) Central Bore 27) Stop 28) Bearing Diameter 29) Restoring Spring Centering Means 30) Rotor Centering 31) Radial Oil Groove 32) Oil Bores 33) Oil Bores 34) Restoring Spring System 35) Axial Stop

36) Oil groove

37) Central Bore 38) Thread 39) Axial Stop 40) Step 41) Axial Stop 42) Lugs 43) Hub 44) Central Bore 45) Bulges 46) Covering Hood

47) Disk 

1-10. (canceled)
 11. A camshaft adjuster, comprising: a drive wheel having an axis of rotation; a stator; a rotor having a degree of freedom of rotation in relation to the stator and being fixed axially in relation to the stator; an adapter sleeve; and a connecting sleeve, the adapter sleeve and the connecting sleeve being arranged coaxially with respect to the axis of rotation of the drive wheel, and the adapter sleeve and the connecting sleeve firstly being connected to each other and secondly fixing the rotor, the stator and the drive wheel in place axially.
 12. The camshaft adjuster according to claim 11, wherein the adapter sleeve is connectable to an end of a camshaft.
 13. The camshaft adjuster according to claim 11, wherein the adapter sleeve is of oil-conducting design.
 14. The camshaft adjuster according to claim 11, wherein the adapter sleeve has an axial stop for fixing the drive wheel in place.
 15. The camshaft adjuster according to claim 11, wherein the adapter sleeve and the connecting sleeve each have an axial stop for fixing the rotor in place.
 16. The camshaft adjuster according to claim 11, wherein the connecting sleeve has an axial stop for fixing the stator in place.
 17. The camshaft adjuster according to claim 11, wherein the drive wheel is mounted on the adapter sleeve.
 18. The camshaft adjuster according to claim 11, wherein the adapter sleeve or the connecting sleeve has a thread.
 19. The camshaft adjuster according to claim 11, wherein the adapter sleeve is connected to the connecting sleeve with an allowance for fit.
 20. The camshaft adjuster according to claim 11, wherein the drive wheel has a step with a diameter at which, the stator is centered and a torque is transmitted. 